[This Truth from Error post first appeared in Scientific American, May 9, 2013. Link: http://bit.ly/ZM3CTT]
Into brains of newborn mice, researchers implanted human “progenitor cells.” These mature into a type of brain cell called astrocytes (see below). They grew into human astrocytes, crowding out mouse astrocytes. The mouse brains became chimeras of human and mouse, with the workhorse mouse brain cells – neurons – nurtured by billions of human astrocytes. Continue reading
The dreaded methicillin-resistant bacteria that increasingly imperil hospital patients, do not defeat it. Nor can tuberculosis bacteria.
This antibiotic is not new. It is in fact natural, and probably a few thousand years old. Nor is it rare: it’s found in human sweat. What is new is that researchers have revealed the structure of this undefeated weapon, and also how it kills a bacterium in one ten-thousandth of a second. Continue reading
Truth from Error guest post in Scientific American. http://bit.ly/11c2jky; or directly: http://blogs.scientificamerican.com/mind-guest-blog/2013/04/01/in-nerve-cells-an-energy-source-nobody-knew-about/
A power source previously unknown. It’s probably this that failed in Woody Guthrie’s and Lou Gehrig’s neurons.
Maybe it’s not surprising that digestion and nutrient metabolism is affected by a human’s 100 trillion gut microbes.
But that physical development of a mammal’s body is altered by changes in gut microbes, this is astonishing.
Just discovered: at puberty, gut microbe populations shift in male and female animals. Before puberty, they’re similar. Gut microbe shifts appear to drive male/female differences in post-puberty sex hormone production. Continue reading
Vision, being familiar, can seem ordinary. Animals of all sorts do it. How remarkable can something universal be?
But shake off sleepy familiarity and amazement re-awakes. What, exactly, happens in a retina cell when it absorbs a photon of light? How, from a fertilized egg, do 100 million retina cells acquire a structure that sends electrical flickers to the brain? Continue reading
Discovery of DNA’s helix structure in 1953 stoked enthusiasm that life’s secret would be soon revealed. The secret would be a chemical one, for complementarity of DNA’s four bases (in the helix ladder’s rungs) suggested a “code” in the molecule. Perhaps it’s like the Morse code, Francis Crick suggested to Sydney Brenner, where two “letters” – dot and dash – translate all written language. Might DNA’s four bases – A, G, C, T — translate all molecules active in life?
It turned out to be more complicated. Continue reading
Nearly 60 years have passed since the Crick-Watson discovery of DNA’s helix structure. “It has not escaped our notice,” they declared in the short Nature article announcing the breakthrough, that the structure implied an elegant mechanism of heredity. DNA replicates itself – that’s the mechanism – but with such complexity that many of its deeds remain concealed despite decades of research.
A couple of them are a little clearer, today. Continue reading
Not exactly cocktail chat, but science journalism’s readers might wonder, swarmed as we are with discoveries big and little on molecular and cellular details. Short answer: “things keep getting more complicated.”
Here are five pigeon-holes for parceling out the news: Continue reading
DNA as heredity’s molecule is one of biology’s greatest discoveries. It seemed to make humanity’s blueprint – our “genome” – discoverable too. Merely identify all genes in human DNA and the job would be done. The gene identifying was achieved in 2001, but instead of man’s blueprint, science got two shocking surprises. Now, one of them has revealed genome complexity so vast that the 21st century may end without our comprehending it. Continue reading
Heart races. Muscles tighten to fight or flee. But what signaled “danger” to your heart? Adrenaline flooded your bloodstream. How did muscles snag those molecules? And what snapped in your retinal cells — vision’s first step — to signal “emergency!” to your brain? How do cells react as swiftly as we know they do? Continue reading